DIY external battery pack for a light?

[h2o_polo_boi]

I was looking at pulling the trigger on the CygoLite TridenX Ni-MH. Instead of shelling out another $70+ on a battery pack, I was wondering if it was possible to make my own. The stock battery pack looks like this:

http://i29.tinypic.com/2lx8i6d.jpg

It is a 6 volt Ni-MH battery pack. I have several Ni-MH batteries @ 1.2 volts each and a 6 AA battery holder. That means I would need only 5 batteries (5 x 1.2 = 6 volts) and must short one slot on the holder. The only thing i'm missing is the DC connector which i should be able to find at a local Radio Shack.

Given all the circumstances, do you think it will work? Is there anything factors I have forgotten consider?

[Zero_Enigma]

The barrel plug looks like a DC 5.5mm OD x 2.1mm ID. You should make sure the batteries are all the same

1. chemisty

2. voltage range

3. capacity

Kind of hard to guage the capacity without having one of those battery analyzer chargers unless there is another way I'm not aware of. I bought a Maha C-9000 for that use as well as I have a ton of NIMH/NICAD's here and wanted to know the mAh on each cell so I could group them for other uses in my packs and lights.

I don't think they make 5 x AA holders. At least I did not find any the last time I did a google search for it. I know the RatShack has 6xAA holders but if you have an electronics shop around better to check them out for those holders they are cheaper there.

If you use the 6xAA just use a wire to connect one of the slots to bypass it like a AA was put in. Or you could solder that wire in to make sure the connection is solid or wrap the wire around and expoxy the wire in.

You may just want to by 6 x AA new and the cells should be pretty even then and take the guess work out of your cells.

[scott L R]

I have a Cygolite, unsure of model with a 6 volt battery. Dual lamps, a 5 and a 10 watt. I bought it used 4 years ago. Started using it agin this fall, after a 6 hour charge only lights for 10 minutes. Dims quickly. Wanting to make my own power source, without buying a new light.

[Pig_Chaser]

Sounds like Zero_Enigma's advice above is about all you need. The only thing i would personally do differently is try prying open the old battery pack and seeing if you can replace the cells inside it.

Also you can get AA's with tabs for making your own battery pack.
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=222

There's allot of those on ebay too, search "AA nimh tab"


Or you can just buy a 6V battery pack:
http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category=470

Again i'm sure you won't have any problem finding those on ebay too.

[h2o_polo_boi]

Kind of hard to guage the capacity without having one of those battery analyzer chargers unless there is another way I'm not aware of. I bought a Maha C-9000 for that use as well as I have a ton of NIMH/NICAD's here and wanted to know the mAh on each cell so I could group them for other uses in my packs and lights.


Is there a way to use alligator clips on the Maha C-9000 tabs to measure the capacity of the battery? I finished making my battery pack. It works but it doesn't last long...less than an hour at full power and 10,000 mAh (5 x 2000 mAh).

Btw, how high of a voltage range can I go? My dad's multimeter measures the battery at 6.25 volts and my battery pack at around 6.44 volts. If I added an extra battery at 1.2 volts, I might be able to get longer life but will I damage the LEDs with the extra voltage?

[Mr York]

Your amp hour figure is wrong. Five batteries in series will give you 6 volts, but the amp hours will remain the same as a single cell. If you put those batteries in parallel, then you would have 10ah, but only 1.2 volts.

[Zero_Enigma]

Is there a way to use alligator clips on the Maha C-9000 tabs to measure the capacity of the battery? I finished making my battery pack. It works but it doesn't last long...less than an hour at full power and 10,000 mAh (5 x 2000 mAh).

Btw, how high of a voltage range can I go? My dad's multimeter measures the battery at 6.25 volts and my battery pack at around 6.44 volts. If I added an extra battery at 1.2 volts, I might be able to get longer life but will I damage the LEDs with the extra voltage?

I have not used aligator clips on the C-9000. I mainly use AA/AAA myself. I have been meaning to look for products to charge C/D cells with the C-9000 but never got around to it.

Off the top of my head I'm thinking if you got one of those AAA -> AA plastic battery convertors you can solder a wire to both ends of the battery convertor to say a quick connect plug which connects to a C/D battery holder. Just take note of the thickness of that battery holders wire guage and pump no more then the max current the wires will take. I think the C-9000 does 2A max charge. I mainly charge at 500-800mA or default 1000mA.

Another thing you can do is check the batteries at www.batteryspace.com and not the 6v batteries charged and normal values then call up Cygolite with that data but don't tell them you want to make your own spare battery. Ask them if the light can handle the highest voltage on the 6v battery pack citing concerns from you charging thier battery pack and using your DMM to check the battery pack (use the excuse the DMM is your battery checker only) and see what they say. If they say it would not be a problem then you're good. If they say there is some regulation or something then well.. I'm not sure what to say/help then. That is a bit beyond me then.


10,000mAh? Are you using 5 x 10,000mAh Maha D cells?

EDIT: Ok read it again. 5 x 1.2v 2000mAh cells = 6v 2000mAh battery pack (it's wired in series to up the voltage but the capacity is the same. If you wired in parallel then the voltage will be 1.2v but the capacity of the battery would increase.). If you have more batteries of the same chem, capacity, voltage range (give or take 5-10% range) try to double the battery power by making a series-parallel battery pack. What that means is you make 2 x 6v 2000mAh battery packs in series then you take the RED-to-RED and BLACK-to-BLACK on both the battery packs to form 1 x 6v 4000mAh battery pack.

I'm not sure what batteries you have left or how your riding is. Regardless a spare battery pack of any capacity is better then up a creek without a paddle when your main battery is dead and you're deep in the woods with no light to return. If the area is safe they ok but if the area is not safe (ie. bad people in the woods after dark) then it can get dangerous. If I recall right the TridentX has various modes of light dimming to save power.

[h2o_polo_boi]

Oh I get it. I never knew what parallel meant until a quick look up on Wikipedia.

My question now is how would I hook up the battery packs together and still have wires to connect to the 9-volt snap connector? If I hook up the only RED & Black cables to the other pack, then I'll have no more wires.

Here's some pics of my rig. I got the 5-pack battery holder from eBay which is the only place I knew of that carried it. Shouldn't be a problem making a parallel pack now since they only come in packs of 8 for $15 and I'll be getting more batteries today. I think parallel is the way to go since I just tested my rig and it only powers the light for about 45 seconds on high! :mad: 2,000 mAh doesn't cut it.

http://i37.tinypic.com/bc21j.jpg

[Maxwell]

Your pack probably has enough capacity to run the light for longer than 45 sec, but is unable to keep up with the high drain rate. I would make another series of 5, and put that in parallel. The 4ah pack should be ale to keep up, and power the light much longer. Also I'd reccomend putting a polyswitch on your pack.

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2590

Nifty little fuse that automatically resets after a few seconds. Protects the cells from short circuits.